Valves are used in internal combustion engines to impede the flow of fluid down a passageway to control a turbocharger. A swing valve may be used in an engine exhaust because of its ability to effectively seal the exhaust passageway, allowing very little fluid to travel downstream of the valve. Swing valves require a very large amount of energy to operate because of their configuration in relation the direction of the flow.
One example of turbocharger control is described in U.S. Pat. No. 5,634,333. In this example it is recognized the need to properly seal an exhaust passage as efficiently as possible. A modified swing valve is used to seal the exhaust passage. The modification includes a spring mechanism and a diaphragm coupled to the valve plate through a series of shafts and pivots. The diaphragm is coupled to the intake manifold allowing the manifold pressure to exert a force on the diaphragm moving the spring and allowing the exhaust valve to be opened. This allows the engine to operate more efficiently because of the use of intake pressure rather than electricity to drive the valve actuator.
Another approach to controlling flow in the exhaust may be a butterfly valve. The butterfly valve requires much less actuation force to open the valve. Unfortunately the butterfly valve ineffectively seals the passageway because of its inability to seat the rotating plate which blocks the flow of fluid in the passage.
The inventor herein has recognized several problems with each of the above approaches. First the modified swing valve may not open under a variety of engine conditions. For example if the manifold pressure is too low the modified swing valve cannot be opened. The use of the intake air pressure to drive the actuator in the modified swing valve reduces pressure which the engine can effectively deliver to the cylinders in the engine reducing the engine speed. The system of pipes used to drive the actuator in the modified swing valve would increase the size and cost of the engine with the addition of extra parts. Finally the butterfly valve may not require a very large actuation force to open, however it may not effectively seal the passageway allowing a great deal of fluid to travel downstream past the valve when it is in a closed position.
In one embodiment, the above issues may be addressed by utilizing a pressure balanced swing valve in an exhaust passage which is used to decrease the amount of power which is needed to operate the swing valve allowing the turbocharger system to work more efficiently, while maintaining an effective seal in the passageway when the valve is in a closed position. This is done through translation of the force which is applied on the valve by the fluid into opposing forces through a simple gearing system. In this way, an efficient usage of flow area may be obtained, and further the approach may be applied to various pipe shapes, including a round pipe. Additionally, in one example, forces may be translated via an internal gear mechanism, thereby providing a compact design.